1. Field of the Invention
The present invention relates to catalyst used in isobutylene polymerization reactions. More particularly, the present invention relates to an alumina support for such catalyst system in which the alumina support has pores formed therein.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
A great number of different types of catalyst systems have been proposed in the past for conducting organic compound conversion reactions. These systems include the use of such things as (1) Metal Oxide BF3 Complexes, (2) BF3 and Liquid BF3 Complexes as Catalysts for Isobutylene Polymerization, (3) Liquid BF3 Methanol Complexes as Isobutylene Polymerization Catalysts, and (4) Solid Isobutylene Polymerization Catalysts. Prior art relevant to these prior art systems is discussed below.
Metal Oxide BF3 Complexes
Inorganic metal oxides, such as alumina, have been provided with catalytic activity in the past by contacting the same with BF3, usually in gaseous form. The contacting is usually followed by hydrolysis and calcination or some other post-treatment. These catalysts generally have limited activity, are not stable and release free BF3 into the reaction products requiring post reaction removal of these residues.
U.S. Pat. No. 2,804,411, assigned to American Oil Company, discloses treatment of a Is stabilized gelled alumina with gaseous BF3. Free BF3 is required to be added to the reaction mixture.
U.S. Pat. No. 2,976,338, assigned to Esso, describes an olefin polymerization catalyst comprising a BF3—H3PO4 complex that may be absorbed onto a solid support.
U.S. Pat. No. 3,114,785, assigned to UOP, describes an olefin isomerization catalyst made by contacting anhydrous gamma or theta alumina with gaseous BF3 at temperatures from about 100° C. to 150° C. for 10 hours or until alumina is saturated. The process of olefin isomerization using the BF3-alumina catalyst is claimed; the composition of the catalyst is not claimed.
U.S. Pat. No. 4,407,731, assigned to UOP, claims catalytic compositions of matter prepared by pre-treating a metal oxide, such as alumina, with aqueous acid and base followed by calcination. The treated gamma alumina is then treated with BF3 gas at temperatures of 308-348° C. at elevated pressure to obtain the final catalyst useful for oligomerization and alkylation reactions.
U.S. Pat. No. 4,427,791, assigned to Mobil Oil Co., discloses a method for enhancing the activity of metal oxides, such as alumina, by treating the alumina with NH4F or BF3, contacting this fluoride containing product with an ammonium exchange solution and then calcinating the final product.
U.S. Pat. No. 4,918,255, assigned to Mobil Oil Co., describes an isoparaffin alkylation catalyst based on metal oxides and aluminosilicate zeolites treated with a Lewis acid, including BF3, in the presence of a controlled amount of water or water-producing material. Excess BF3, to that needed to saturate the metal oxide, is used requiring post reaction BF3 removal.
U.S. Pat. No. 4,935,577, assigned to Mobil Oil Co., describes a catalytic distillation process using a non-zeolite metal oxide activated with BF3 gas. Excess BF3, above that needed to saturate the metal oxide is used requiring post reaction BF3 removal.
BF3 and Liquid BF3 Complexes as Catalysts for Isobutylene Polymerization
The homogenous catalytic polymerization of olefins using gaseous BF3 and liquid BF3 complexes is well known. The polymers generally so produced are of the highly reactive type wherein a large percentage of the polymer contains terminal double bonds or has a high vinylidene content. All of these processes require post-reaction removal of the BF3 catalyst.
U.S. Pat. No. 4,152,499, issued to Boerzel et al., describes the synthesis of polyisobutylene having a degree of polymerization of 10-100 units using a blanket of BF3 gas as the catalyst. The polyisobutylene product was then reacted with maleic anhydride in yields of 60-90% indicating a large portion of vinylidene end groups.
U.S. Pat. No. 4,605,808, issued to Samson, describes production of a polyisobutylene having at least 70% unsaturation in the terminal position. An alcohol complex of BF3 was used as the catalyst. Complexing the BF3 seems to give better control of the reaction and higher vinylidene content.
U.S. Pat. No. 7,411,104, assigned to Daelim Industrial Co., describes a method for producing highly reactive polyisobutylene from a raffinate-1 stream using a liquid BF3 secondary alkyl ether-tertiary alcohol complex. The process requires low reaction temperatures and the catalyst complex is not stable and must be made in situ. The catalyst must be removed from the reactor effluent by a post reaction treatment process.
U.S. Pat. No. 5,191,044, issued to Rath et al., discloses a process for preparing polyisobutylene in which the BF3 catalyst is completely complexed with an alcohol such that there is no free BF3 in the reactor or in the reaction zones. An excess of alcohol complexing agent is required to assure that no free BF3 is present. The reaction times are on the order of 10 minutes with reaction temperatures of below 0° C.
Rath, in U.S. Pat. No. 5,408,018 describes a multistage process for preparing highly reactive polyisobutene with a content of terminal vinylidene groups of more than 80 mol % and an average molecular weight of 500-5000 Dalton by the cationic polymerization of isobutene or isobutene-containing hydrocarbon feeds in liquid phase with the aid of boron trifluoride as catalyst and at from 0° C. to −60° C. comprises polymerizing in the presence of secondary alcohols with 3-20 carbon atoms and/or ethers with 2-20 carbon atoms.
Olefin polymerization, especially isobutylene polymerization, is an exothermic process. Control of reaction temperature is critical to product quality, catalyst life, degree of polymerization and obtaining the desired pre-selected properties. In the patents cited above, the reaction temperature was controlled by dilute olefin monomer concentration, complexed catalyst, multi-stage reactions and/or long reaction times and low reaction temperatures. Low reaction temperatures increase energy requirements; long reaction times or dilute feed streams increase equipment size and equipment cost (capital expenditures).
Liquid BF3 Methanol Complexes as Isobutylene Polymerization Catalysts
U.S. Pat. Nos. 6,525,149, 6,562,913, 6,683,138, 6,884,858 and 6,992,152, to Baxter, et al. al, describe an olefin polymerization process in which the polymerization is carried out in the tube side of a heat exchanger under turbulent flow conditions. The reactor design allows for very effective and efficient removal of the heat of reaction such that relatively high feed rates and concentrated feed streams may be used. BF3-methanol complex is used as the catalyst and because this complex is particularly stable, higher reaction temperatures may be used. The BF3-methanol catalyst complex may be preformed, formed in-situ by separate injection of the methanol complexing agent, or a combination of both.
The BF3 methanol complexes are very stable allowing for higher isobutylene polymerization temperatures not possible with other BF3 oxygenate complexes, particularly higher alcohols, secondary alcohols, ethers and the like. Also, because higher reaction temperatures may be used, reaction rates are increased.
However, in all of the patents cited above, the BF3, or at least portions of the BF3, catalyst are soluble in the polymer products. Residual BF3 is detrimental to product quality and must be removed as quickly as possible. Hence, these processes must employ some kind of catalyst quench and catalyst removal steps subsequent to the reaction. The quenched BF3 streams cannot be recycled and the BF3 is lost.
Solid Isobutylene Polymerization Catalysts
Isobutylene and butylene polymerizations have also been conducted using solid catalysts, particularly Friedel-Crafts type catalysts such as AlCl3. The advantage to these processes is that the catalyst is a solid and is not soluble in the product. Catalyst removal and product purification is much easier than in the BF3 catalyzed reactions
U.S. Pat. No. 2,484,384, assigned to California Research Corporation, U.S. Pat. No. 2,677,002, assigned to Standard Oil Co., U.S. Pat. No. 2,957,930, assigned to Cosden Petroleum Corporation and U.S. Pat. No. 3,119,884, assigned to Cosden Petroleum Corporation, all describe AlCl3 catalyzed butylene polymerization processes using a fluidized bed reactor system.
U.S. Pat. No. 4,306,105, assigned to Cosden Petroleum Corporation, describes a chlorinated alumina catalyst prepared by reacting pure alumina with pure chlorine. A fluidized bed reactor is utilized for butene polymerization.
Solid catalysts have also been used to produce olefin polymers with a high proportion of terminal vinylidene groups.
U.S. Pat. No. 5,710,225, assigned to Lubrizol, claims the use of phosphotungstic acid salt to polymerize C2-C30 olefins to produce polymers with molecular weights in the range of 300-20,000. The use of phosphotungstic catalyst, in a fixed bed reactor, is also described, but the flow rate is low and is generally operated as a plug flow reactor. The resulting polymer has an undesirable very high polydispersity. The fixed bed reactor as described in the example would not be economically feasible.
U.S. Pat. No. 5,770,539, assigned to Exxon Chemical Patents, Inc., discloses heterogeneous Lewis acids polymerization catalysts, such as BF3, immobilized in porous polymer substrates. The BF3 is complexed with the aromatic rings of cross-linked polystyrene copolymers.
U.S. Pat. No. 5,874,380, assigned to Exxon Chemical Patents, Inc., claims a solid state insoluble salt catalyst system for the carbocationic polymerization of olefin monomer in the presence of polar or non-polar reaction medium which comprises at least one salt of a strong acid and a carbocationically active transition metal catalyst selected from Groups IIIA, IVA, VA, and VIA of the Periodic Table of the Elements.
U.S. Pat. No. 6,384,154, assigned to BASF Aktiengesellshaft, discloses a process for preparing halogen free, reactive polyisobutylene by cationic polymerization over an acidic, halogen free heterogeneous catalyst comprising oxides and elements from transition or main group I, II, III, IV, V, VI, VII or VIII of the Periodic Table of the Elements. The polymerization is carried out in a fixed bed reactor.
The solid, heterogeneous butylene polymerization catalysts cited above do solve the problem of catalyst residues in the reactor effluent, thereby eliminating the need for post reaction treatment. However, conversions are low, space velocities are low and reaction temperatures are low.
BF3 activated metal oxides are not described in the prior art as polymerization catalysts for the manufacture of polybutene or polyisobutylene. In fact, U.S. Pat. No. 6,710,140 assigned to BASF Aktiengesellshaft, claims the use of alumina as a solid deactivator to absorb BF3 catalyst residues from polyisobutylene reactor effluents. The resulting BF3-alumina complex is described to be not catalytic.
U.S. application Ser. No. 13/50,956 describes a catalyst system for the heterogenous catalysis of organic compound conversion reactions. The system includes a reaction product of a BF3/alcohol catalyst complex and an activated metal oxide support for the catalyst complex. In particular, the activated metal oxide support is an alumina support. In experiments conducted with the process identified in this application, it was found that the alumina support utilized alumina beads within a fixed bed. In general, these alumina beads had a relatively short catalyst life. The use of such solid beads were somewhat difficult control. These beads produced a lower molecular weight because of a drop-off in conversion rates. As such, is necessary to adjust temperatures in order to control the reaction process. Ultimately, only a surface reaction occurred on these alumina beads. Ultimately, lower conversions occurred and a higher molecular weight product resulted. As such, there was a need to modify the alumina support so as to enhance the process.
It is an object of the present invention to provide a catalysis process which enhances the diffusion of the catalyst complex on the alumina support.
It is another object the present invention to provide a catalysis process which facilitates the flow of long chain polymers.
It is another object of the present invention to provide a catalysis process which enhances the life of the catalyst.
It is another object the present invention to provide a catalysis process which makes it easier to control the reaction.
It is still further object of the present invention to provide a catalysis process which produces a product being a higher molecular weight with lower temperatures.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.